M1 Abrams

Intensive works to develop new main battle tank began in the USA after the end of MBT-70 program (Main Battle Tank of 70-ties) cooperated with German Federation Republic in 1970. In year 1973 there was published US Armed Forces competition for the best main battle tank's project. Competition won "Chrysler" corporation with XM803 test tank in 1976. It's developers paid great attention to crew safety and armament. Tank got indexation XM1 and after some improvements begun it's serial production named M1 "Abrams" in honor to General Abrams who commanded US forces in Vietnam.

First serial M1 "Abrams" was produced in February 1980 in Ohio state, Lima city, in US national tank plant. Since 1982 tank was also built in Michigan state, Voren city "Detroit Arsenal" tank plant. At the same time "General Dynamics" corporation got license to built them. Till 1985 there were built 3 236 this type main battle tanks. Since 1986 to 1990 were built 840 tanks annually for US Ground Forces and in year 1991 and 1992 there were produced 691 tanks for US Marine Corps.

Main battle tank has classic arrangement with frontal drivers compartment. Hull and turret are welded with multi-layered frontal armor similar to British armor "Chobhem". Similarly to British main battle tanks "Chieftain" and "Challenger", driver-mechanic with closed hatch is placed in half-lying position. It allowed greatly incline frontal armed plate in vertical inclination level such increasing defense from armor-piercing projectiles. Driver-mechanic use motorcycle-type steering wheel connected with automatic transmission.

M1 "Abrams" is armed with M68E1 105-mm rifled gun (modified British L7 gun), fitted with ejector and thermo sleeve body stabilized in two planes. Main gun is placed in armored welded turret and is almost similar to main gun used on M60. US specialists say that M1 twice surpassed M60 in overall characteristics. Tankís commander and gunner are placed right from main gun and loader Ė left. Main combat ammunition load (44 projectiles of 55) is placed is isolated rear turretís part. Access to ammunition load is available only with opened armored screens. Other ammunition storage is placed in armed containers placed in tankís body (8) and in front of the loader (3).

Combat ammunition load consists from M735 undercaliber wolfram head armor-piercing projectiles with separating case, M774 and M883 with precipitant uranium head as well. M737 is training projectile and is also used by M1 "Abrams".

Additional armament consists from coaxial 7.62-mm machine gun, other the same caliber machine gun placed in front of loaders hatch and 12.7-mm anti-aircraft machine gun mounted on commanders observation turret. Tank's commander is able to use it with closed hatch. Main battle tank is fitted with thermo smoke equipment and 6 smoke grenade launchers, mounted on the turret boards.

M1 "Abrams" has modern enough main gun fire control equipment. There was published information that ďAbramsĒ defeated target in 1 850 m range from first shot, moving in cross-country terrain with 40 km/h speed. Main sight used by gunner is combined day-night optical device with built-in laser rangefinder and sighting line stabilizer in vertical plane what allows to execute quiet effective fire moving. Tank is also fitted with additional telescopic device. Tankís commander is able to see gunnerís sight view, which allows making battlefield observation and sighting at once. M1 "Abrams" is able to notice tanks in 3 000 km range at night and in 1 200 in fog. Commander is equipped with periscope anti-aircraft machine gunís sight and six observation blocks in turrets perimeter with 360-degree view.

M1 "Abrams" became first western main battle tank fitted with gas turbine engine. First world main battle tank fitted with such engine was T-80, entered service in Soviet Armed Forces in 1976. M1 "Abrams" is fitted with AGT-1500 "Avco Lycoming" company engine which has 1 500 h.p. in 3 000 rate/minute. Engine is multi-fuel and uses kerosene, diesel and petrol. Engines service life till major repairs is 1 800 hours or 19 000 km while tank diesel engines serve only 600 Ė 900 working hours.

M1 "Abrams" has hydromechanic transmission made in one block with engine and has four forward and two backward gears. Tank turning radius is changing using consistent hydro changeable gear in turning mechanism. Chassis has 7 rubber laid bearing rolls, two track supporting bearings, leading and tracking wheels from each side. Main battle tank uses track with rubber-metallic hinge and full-rubber tracks. Monotorsion suspension with adjustable clearance allows changing bearing rolls dynamic clearance in 381 mm and full in 581 mm. Chassis and hulls boards are covered with anti-cumulation screens.

M1 main battle tank has high power to tone ratio in 28 h.p./t what determines high mobility. Tank has maximum road speed in 72 km/h and cross-country - about 55 km/h. Moving from stop position it reaches 30 km/h speed in 6.2 s. It is able to overcome 30 degrees elevations, 1.24 m vertical steps, 2.77 m trenches and fords unprepared 1.2 m water obstacles.

Main battle tank is equipped with Nuclear, Biological, and Chemical mass defeating defense system, which provides cleaned air to crewís face masks and increases compartmentís air pressure to prevent passing radioactive dust and poisons. M1 "Abrams" is also fitted with radiological and chemical reconnaissance equipment, fire prevention system, heater and communication sources.

Developing main battle tank a great attention caused technical maintenance and repairs simplifying problems. For example engine can be changed in field conditions in 30 minutes, while the same operation in M60 lasted approximately 4 hours.

There were developed some M1 main battle tanks modifications. The first, M1E1 was built in 1981. till 1985 there were built 894 such tanks. They differed in 120-mm smoothbore gun and increased power projectiles. In the end of 1986 new M1A1 modification entered service in US Armed Forces. It had increased firepower and defense. Since 1991 begun production of M1A2 differing from M1A1 in new thermovision sight, modernized laser rangefinder, battlefield informational system, built-in dynamic armor and modernized commanders observation turret.